The two figures below show the influence of melatonin intake respectively on REM and deep sleep. The intake was with 3mg of Melatonin (timed released) always taken between 10 and 11 PM (according to a study conducted with patients with reduced REM sleep duration, this time window seems the best for influencing positively REM sleep duration).
On the figures, the left bar (0) represents the average time spent without melatonin intake, the right one (1) with, and #data on the top of the bars gives the number of nights that have been collected.
The results tend to show an increasing of time spent in REM sleep with melatonin but does not seem to influence time spent in deep sleep.
Bottom line, more data is required (only 25 nights with melatonin intake have been gathered within this time frame).
Fig. 1: Influence of melatonin intake on REM sleep.
Fig. 2: Influence of melatonin intake on Deep sleep.
Time Frame of the experiment
30 Sept. 2012 – 6 Apr. 2013
References & Links
 Reference of the study mentioned above: “Melatonin in patients with reduced REM sleep duration: two randomized controlled trials”. Kunz D, Mahlberg R, Müller C, Tilmann A, Bes F. 2004.
 Experiments conducted by Gwern on Melatonin.